AuthorKamat, Anuja Ganesh
Keywordssplit concrete model
reinforced concrete beams
prestressed concrete beams
Committee ChairHaldar, Achintya
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractSplit Concrete Model (SCM) is a unified approach towards modeling shear behavior in concrete. SCM is essentially a rational model which is evaluated and modified using a large experimental database.The shear strength of the concrete beam is modeled as the sum of the contribution of concrete, transverse reinforcement, longitudinal reinforcement and bond between concrete and longitudinal reinforcement. Concrete does not contribute to the shear strength after the formation of the crack. In SCM, this is shown to be accurately modeled by only considering the second branch of the critical crack while computing the contribution of concrete towards shear strength of the beam. Formation of the second branch of the critical crack and immediate subsequent failure of the beam has been compared to the split-cylinder test, which forms the conceptual basis of SCM.SCM computes the concrete contribution using the split tensile strength and the area under compression of the concrete beam. For cases where a split-cylinder test is not performed, a mathematical model is proposed to compute the split tensile strength using the compressive strength of concrete available from experimental results. This model is proposed using advanced statistical methods, including weighted residuals and Box-Cox transformation and is validated using various statistical procedures. The transverse reinforcement contributes to the shear strength of the concrete beam only after the formation of the crack. In SCM, this is shown to be accurately modeled by only considering the first branch of the critical crack while computing the contribution of the transverse reinforcement towards shear strength of the beam, instead of the conventional approach of considering the entire length of the crack. The contribution of the longitudinal steel and bond between concrete and longitudinal steel and concrete is accurately modeled unlike the conventional approaches which do not consider this contribution.Evaluation using the database shows that SCM can predict accurate results for all ranges of strength, depth, reinforcement ratio, and shear span to depth ratio of the beam. This shows that all the influencing parameters for concrete shear strength have been correctly modeled in SCM. SCM gives more accurate results as compared to current codified approaches as verified with design examples. Finally, specific recommendations have been made indicating how the shear design requirements in the current ACI code can be modified.
Degree ProgramCivil Engineering
Degree GrantorUniversity of Arizona
Showing items related by title, author, creator and subject.
Nondestructive evaluation of bar-concrete interface in reinforced concrete structuresKundu, Tribikram; Ehsani, Mohammad R.; Na, Won-Bae (The University of Arizona., 2001)The feasibility of detecting and quantifying delamination at the interface between steel (or GFRP) bar and concrete using ultrasonic guided waves is investigated in this study. These waves can propagate a long distance along the reinforcing steel (or GFRP) bar or concrete beam as guided waves and are sensitive to the interface bonding condition between the steel (or GFRP) bar and concrete. The traditional ultrasonic methods are good for detecting large voids in concrete but not very efficient for detecting delamination at the interface between concrete and steel (GFRP) bar since they use reflection, transmission and scattering of longitudinal waves by internal defects. In this study, special solid couplers between the steel/GFRP bar (or concrete beam) and ultrasonic transducers have been used to launch cylindrical guided waves (or Lamb waves) in the steel/GFRP bar (or concrete). This investigation shows that the guided wave inspection technique is an efficient and effective tool for health monitoring of concrete structures.
A transient model for decomposition and ablation of concrete during a molten core/concrete interactionKilic, Arif Nesimi, 1963- (The University of Arizona., 1991)A simple approximation for predicting the concrete erosion rate and depth is derived based on heat balance integral method for conduction with the time dependent boundary conditions. The problem is considered a four-region model including separate, moving heat sinks at the boundaries due to endothermic decomposition reactions. Polynomial temperature profiles are assumed and the results are compared to previous experimental data and other analytical solutions. Since the technique provides an approximate temperature distribution on the average, it does not give the real temperature evaluation but provides a simple prediction of the erosion rates in terms of the parameters that are important during the physical phenomena. Because of its simplicity and reliability, the model might be useful of the larger molten core/concrete interaction models.
Effect of fine aggregate's surface texture on creep in asphaltic concreteJimenez, Rudolf A.; Farazandeh, Mahmood, 1969- (The University of Arizona., 1990)This report is concerned with the study of the effects of fine aggregate's surface texture on creep in asphaltic concrete mixtures. The "Time Index" method was applied to measure the degree of angularity and roughness of fine aggregates. The creep test method introduced by Shell Petroleum Company was studied and the review of literature appears to credit this method. A simple lever arm loading system was set up in a hot room with a temperature of 104 F. Variables of air void content, asphalt grade and content were studied in three different blends containing fine aggregates of low, medium and high surface texture indices. The creep test was easy to perform and during this study it showed to be a good reflectant of the influence of the effect of aggregate surface texture on plastic deformation of asphaltic concrete mixtures.